ML19254D646
| ML19254D646 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 10/23/1979 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML19254D645 | List: |
| References | |
| NUDOCS 7910290264 | |
| Download: ML19254D646 (4) | |
Text
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CONSUMERS POWER COMPANY Docket 50-155 Request for Change to the Technical Specifications License DPR-6 For the reasons hereinafter set forth, it is requested that the Technical Speci-fications contained in Facility Operating License DPR-6, Docket 50-155, issued to Consumers Power Company on May 1,1964, for the Big Rock Point Plant, 3xe changed as described in Section I below:
I.
Change Revise Section 6.1.2 (Column 4 of Items 2 and 3) to read:
" Sensor Scram Setting Trip Device and Tolerance Lov Reactor h 610'5" Water Level (4 Level Switches)
Lov Steam Drum 2h 8.5" Below Steam Water Level (k Drum Center Line Level Switches)
(Calibrated for Operating Te=pera-ture and Pressure)"
II.
Discussion A.
Low reactor water level. This change removes the 1" tolerance on the set point while maintaining the limit of the previously stated minimum.
(Present Technical Specifications require 610'6" 1".)
B.
Lov steam drum level. This change allows the set point to be calibrated for normal operating pressure and temperature (steady state power). The present Technical Specification implies that the calibration applies to all primary system conditions when the reactor head is on and control rods are withdrawn from the core.
As described in Licensee Event Report 79-22, evaluation of level instrumen-tation identified a potential deficiency. The deficiency was related to the elevated temperature in the level instrumentation reference leg which could result in flashing of the reference level liquid during a rapid pri-mary system depressurization. Under these conditions erroneous high-level readings would occur.
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To resolve this deficiency, the instrument is being modified to reduce the referance leg temperature. This is being done by removing the jacket and heat clamps that currently exist around and between the variable leg and the reference leg of the level instrument. Some heat shielding may also be pro-vided to further isolate the heating effects of the variable leg on the reference leg. These modifications vill reduce the temperature in the reference leg to 6 bout 250 F and vill prevent erroneous high-level reading during a rapid primary system depressurization event.
The modification described above vill significantly reduce the temperature compensation ability of the level instrumentation. To assure that the appropriate set points are maintained for initiating safety system action, the following changes are being made.
LOW REACTOR WE'ER LEVEL The Technical Specifications change vill allow a higher safety system set point level to be selected such that under all operating and accident con-ditions the actual reactor water level set point vill not be less than 610'5".
LOW STEAM DRUM WATER LEVEL For drum level measurements, operating restraints do not allow establishment of a set point high enough to accommodate the drift associated with loss in temperature compensation while meeting the present specification under all operating conditions (specifically during primary system heatup and cooldown).
The proposed specification che ige requires the instrument to be calibrated for the full power operating conditions. While the actual set point level vill be lower at other temperatures, the minimum primary system liquid inventor'/
assumed in the accident analysis vill be maintained.
For conditions which occur during normal system heatup and cooldown, the actual lov steam drum vater level set point =ay be lower than that specified for full power operation. However, the total primary systems inventory (mass) at the reduced set point vill be greater than or equal to either that aseumed in the accident analysis or that which would be available at the set point during normal operating conditions. Table 1 shows the relationship of the primary system mass as a function of system temperature (and corresponding scram point).
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TABLE 1 Lov Drum Level Scram Vs System Parameters With Temuerature Compensation Removed From Steam Drum Level Instruments
- Actual Scram
- Mass at Psys (Psia)
Tsys ( F)
Point (In)
Scram (Lbm)
- "I Mo 1,350 582
-8" 38,500 100 1,000 5k5
-10" 38,500 100 500 467
-12" 40,300 105 14.7 212
-16" 43,h00 113
" Scram point is the actual drum level below center line.
- Mass in the system above the core at the corresponding low drum level.
- Percent mass above the core as compared.to 1007, power at 1,350 psia with drum level at 8" below center line.
The accident analysis remains valid.
III.
Conclusions Based on the foregoing, both the Big Rock Point Plant Review Committee and the Safety and Audit Review Board have concluded that this change is accept-able from a safety standpoint.
COIISUMERS POWER COMPAIIY i Lb0 R B DeWitt Vice President-Iluelear Operations Sworn and subscribed to before me this 23rd day of October 1979 flR b/-~
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Dorothy H Battkus,liotary Public Jackson County, Michigan My commission expires March 26, 1983 1221 077 3
6.1.2 Reactor Safety System During Power Operation The following tabulation gives the arrangement of the reactor safety system that shall be effective during power operation:
Trip Contacts Coincidence Scram Setting Warning Sensor and in Each in Each and Instrument Annunciation Trip Device Channel Channel Tolerance Special Features Ranges Trip Set Point liigh Reactor Pres-2 1 Out of 2 5015 Psi Above 100-1700 Psig 515 Psi Above sure (4 Pressure Reactor Oper-Reactor Operating Switches) ating Pressure Pressure Low Reactor Water 2
1 Out of 2 Elevation Closes containment Fixed Level Level (4 Level 2.610'5" sphere isolation Trip Point Switches) valves. If reactor No Range pressure is less than 200 psig, actuates core spray system.
(Note: Spray water will not enter reactor vessel until reactor pressure drops below fire header pressure.)
Low Steam Drwa 2
1 Out of 2 2,8.5" Below
-30" to +30"
-4" Below Steam Water Level (4 Steam Drum Water Drum Center Line Level Switches)
Center Line (Calibrated for Operating Temp and Pressure) 1 lain Stema Line 2
1 Out of 2 5015 Percent of Position Switch Backup Isolation rs)
Full Closure Trains Adjustable Valve Closure (4 I'd Full Valve Travel Position Switches) ~
liigh Condenser fh,
2 1 Out of 2 8.010 5" of Hg Bypassed by pressure 0 - 30" Hg Vac Pressure (4 Pres cy)
Absolute Pres-interlock as described sure Switches) sure in Section 6.1. 3.